In the past few years there has been an increased interest in the utilization of fiber interconnects in the telecommunications industry. Typically, fibers used in telecommunications are deployed underground and can potentially utilize a vertical cavity surface emitting laser (VCSEL) as the light source. It is generally well known in the art that these types of fibers can only support one channel. To increase the data transmission rate at which these fiber interconnects operate, parallel data communication techniques are required. In general, parallel data communication technology requires the use of more than one channel, thus more than one beam of light, in the fiber interconnects. In that these telecommunications fibers are generally deployed underground, it is very expensive to deploy additional fibers to achieve multi-channel parallel data communication thereby increasing data transmission rates.
To achieve this multi-channel parallel data communication, wavelength division multiplexing (WDM) is utilized. In WDM, different wavelength beams can be combined into one fiber interconnect, with each wavelength beam being individually modulated to carry data bits, or information. Once the combined beam has reached its destination, it can be easily separated using demultiplexing techniques. In general, different wavelength beams can be multiplexed into the same fiber as different data channels. By utilizing this WDM technology, there is no need to redeploy the fiber interconnects already positioned underground to achieve high speed data communication through parallel data transmission.
To increase the efficiency of the system, the packing density of the light source, the VCSELs, can be increased by making the wavelength difference between the neighboring channels, or VCSEL beams, as small as possible, but large enough to be demultiplexed without severe cross-talk between the channels. In addition, the wavelength of the individual beams must be stable to temperature and bias current variations so as to allow the receiving end to distinguish between different channels. To achieve the highest possible packing density and resolution between the channels, the device should operate at single mode frequency. Using conventional VCSEL technology, however, it is difficult to achieve multiple single mode wavelength in a single array.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide a new and improved laser beam light source for use in multi-channel parallel data communication.
It is another object of the present invention to provide stable single high order mode laser source fabricated as a annular waveguide VCSEL array.
Another object of the invention is to provide a reliable single high order mode VCSEL array characterized as emitting a plurality of laser beams of varying wavelength.
Another object of the present invention is to provide for a method of fabricating an annular waveguide VCSEL array that includes the etching of a plurality of mirror stacks of varying widths so as to force the lasing mode of each VCSEL device to be confined to an annular region thereby forcing each VCSEL to operate in a single high order mode at a specific wavelength.